The continuing posts at Apple's tech support site and at online forums show users with existing iPhone and iPads frustrated by a flurry of different problems, including a "grayed out" Wi-Fi option, dropped connections, slow connection speeds, and having to connect manually to a Wi-Fi access point. Separately, there are posts by some owners of the new iPhone 5, released last Friday, also about Wi-Fi problems.

Confusedly, these are problems that are unrelated to the Wi-Fi glitch last week when iOS 6 was first released. In that situation, the iPhone or iPad pings an Apple Website to determine if the device is on a hotel or airport Wi-Fi network and needs a network "terms of agreement" page. That webpage was temporarily offline, but its absence prevented a lot of users from getting Wi-Fi access for a few hours. But it was quickly fixed.

Because of the nature of online postings, it's difficult to see patterns or to gain a sense of how widespread these problems are. When queried last Friday, an Apple PR spokesman replied via email "Thanks for bringing this to my attention." Two follow-up emails asking for a statement from Apple have not been acknowledged by either of two PR persons contacted.

A typical post on Apple's own support boards is this one from bigfirefighter, in Ohio, who posted Tuesday morning September 25: "I have been through 2 levels of Apple Support and they can't help, they said they "kicked it up to the engineers". IPhone 4 updated at the same time as iPad, which works perfectly. Cannot turn on wifi on the phone since it is grayed out. Did several hard resets, restored twice, restored to factory settings once, reset network connections twice, nothing works..."

That post was part of a thread titled "iOS 6 WiFi Disabled" which by Tuesday afternoon had received 70,496 views, and 835 comments.

Another poster named VeeDom reported the same problem. "I called Apple Care and told me that they know about this issue and are working on it for a new release of IOS6 to fix this... Until now, we are stuck!" He added a new twist: "Also, just found out that aside from the greyed wifi switch, I can't seem to detect my [iPhone] 4S on my macbook via wifi (using personal hotspot) even if it is enabled. I'm not sure if it is related to the wifi issue but you may want to check if yours is working."

Solutions seems as inexplicable as the problems. Kenishialala posted: "I had the same problem since yesterday but thank goodness it's back now! I've been restoring my iphone for I can't remember how many times now. But for the nth time today, it finally worked! The original plan was to downgrade to iOS 5.1.1. I failed twice so on the third time, I decided to bring back the iOS6. MIRACLE, I am now able to use the wifi again. Toggle it on and off and connect it to our Wifi."

By Tuesday afternoon, MacRumors.com forums had 10 separate threads related to Wi-Fi issues with iOS 6 or the new iPhone 5: such as "Painfully slow WiFi on new iPhone 5," "WiFi Sync Terrible on iOS 6?," "No WiFi on certain access points," and "Persistent WiFi + iOS6." But keep in mind that many of the earlier posts on these threads are related to the original Web-based Wi-Fi glitch.

New owners of the iPhone 5 frustrated by similar problems, as posts at the online forums of MacRumors.com show.

Commenter otis123 wrote "My [iPhone] 5 is having quite a bit of trouble with my AirPort Extreme [access point]. Slow throughput and its having a hard time staying connected. My other iOS devices are fine as always, even my 3rd gen iPad on iOS 6."

Another poster, vanc, had a similar experience, with his Apple Airport Express access point. "Throughput was horrible, and disconnected from my Airport express constantly. In the same location, my iPhone 4, iPad 1 & 3 all worked perfectly." His solution: "In order to make iPhone 5 happy, I purchased an Airport Extreme yesterday and used the existing Airport express as an extender. This solved the problem perfectly. Now on iPhone 5, I don't have random dropouts and throughput is inline with my other iDevices."

ZenErik found a wide performance gap between his laptop and the new iPhone: "I'm getting 10 - 12 Mbps down on my laptop and anywhere between .3 and 10 Mbps on my iPhone 5. Extremely inconsistent. ping has gone anywhere from 60 - 300 ms. Up speed has remained between 5 and 6 Mbps for the most part."

It worked for another user, but others said it failed. One of them was danilko1, who reported that the new iPhone 5 worked "pretty good" out of the box and over the weekend, but then it failed to connect at work and then at home. "I noticed GPS was active. I killed all apps. Rebooted. Then not at first, but within 10 minutes, something healed and now it's running good again. This is strange. I hope it's not a common thing. I hardly ever had to reboot my other iPhones."

WLAN vendors, when they're willing to comment, say they're not seeing any surge of problems.

"We have upgraded dozens if iOS devcies internally and have not seen any performance degradation," according to Bruce Miller, vice president of product marketing, networks, at Xirrus, a WLAN vendor. "We have not received any communications from our customers with issues related to iOS upgrades either, either directly into [Tech] Support or via social channels."

Ruckus Wireless and Aerohive also said there have been no problem reports so far. Cisco declined to comment.

A teacher, identified as bravescoach, started a thread on Apple's site describing problems at at Indianapolis-area school with 750 students and a mix of personally-owned mobile devices, though "hundreds" have iPhones and iPads. The school's Wi-Fi network is based on Cisco Aironet WLAN gear.

"There is definitely an issue where iPhone 4S and iPad 3rd generation devices are "unable to join network" after updating to iOS 6," he writes. "Needless to say it is wholly impractical to revert firmware on any of these machines just to deal with two [types of] devices. Each of these devices were fully capable of connecting while on iOS 5.1.1."

Other iDevices, including iPhone 3GS, iPhone 4, iPod touch 4th gen, and iPad 2 "all work fine." According to this poster "several schools" in the area have run into problems. His own iPad 3 works, updated to iOS 6, works on his home network, with a Linksys router, but not on the school's WLAN.

A variety of suggestions have been put forward including resetting or changing the authentication/encryption being used by the client devices and the network. But that's not an option for many enterprise WLANs.

Users with working iPhone 5 Wi-Fi are seeing some startling increases in throughput, as some of the comments above show. This is due almost entirely to the fact that it now supports Wi-Fi connections over the 5-GHz band instead of just 2.4 GHz. [see "FAQ: iPhone 5 and 5GHz Wi-Fi"]

Xirrus this week has run a series of tests with the new iPhone 5, connecting to its Wireless Array access point. One set of tests compared Wi-Fi performance of iPhone 5 on 2.4GHz with 20 MHz-wide channels and on 5GHz with 40 MHz-wide channels. The second set of tests Wi-Fi performance of the iPhone 4S on 2.4 GHz with 20 MHz-wide channels. Each test measured the throughput and time to send and receive a 100MB file.

For iPhone 5 on 2.4 GHz: throughput was 42.24Mbps and 19 seconds uploading, and 38.31Mbps and 21 seconds downloading the file.

The iPhone 4S had comparable numbers in 2.4 GHz: 32.18Mbps and 20 seconds uploading; and 40.23Mbps and 25 seconds downloading.

But on 5GHz, with its uncluttered spectrum and wider channels, the iPhone 5 showed an astounding improvement: throughput was 80.39Mbps and 9 seconds uploading, and 67.05Mbps and 12 seconds downloading.

At least for non-streaming applications, that kind of speed can prolong battery life because the radio connection is active for much shorter periods of time for the same amount of data being transferred.

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